How to change the starting conditions of the "Fly the Havilland Beaver" model in Simulink?

Hello,

When running the 1.78 version of the model, the airplane already starts with non-zero roll, pitch and yaw rates, as well as angular rates. Since I'm trying to trim and linearize the model in order to simulate a steady-state flying condition, I need to make sure that the angles and angular rates all start from 0 at t=0.

I've already tried changing the parameters in the 6DOF block with no success: even if I set the initial angular rates to 0, the airplane starts rolling and yawing even if there is no input from my joystick.

Thanks in advance for answering and I apologize for the inconvenience

Answer 1

[Garmit Pant]

Hello Francesco Celino

From what I gather, you are using the “Fly the Havilland Beaver” in Simulink using a joystick and you want to trim and linearise the model. The air is starting with non-zero roll, pitch and yaw rates.

This is expected behaviour because the airframe is not at a trim condition. To trim and linearise the model, you’d need to set the initial operating point. This can be done using the Model Linearizer App. You can set the Joystick Input to “None” and proceed to trim the model using the app.

Follow the following steps to trim the model and find the initial operating point:

• Find the “Model Linearizer” app in the Apps section.

• Select the “Trim Model” option in the “Operating Point” dropdown.

• Set the state operating specifications including the values for the states and which ones to keep steady. Click on “Start Trimming” after setting the conditions. This will give you the initial operating point for the trimmed model.

For further understanding, you can follow the following video guide to trim and linearise the model:

https://www.mathworks.com/videos/trim-linearization-and-control-design-for-an-aircraft-68880.html

I hope you find the above explanation and suggestions useful!